The present invention relates generally to ceiling grid systems including individual support runners and more particularly to a specific way in which the runners are interlocked together.
Suspended ceiling systems are well known in the art. A typical system of this general type includes a number of longitudinal runners which interlock together to form an overall grid for supporting ceiling panels or tile, light fixtures and the like. While most of the suspended ceiling systems of the prior art typically include these interlocked runners, the runners themselves and the specific way in which they are interlocked together vary from system to system. For example, in a system disclosed in U.S. Pat. No. 3,292,332 (Jahn), the adjacent ends of colinear runners are interlocked together through transverse runners by means of separate interlocking clips. In a system disclosed in U.S. Pat. No. 3,848,385 (Thompson), the runners, which are entirely different than those used in the Jahn system, are interlocked together in groups of four perpendicular runners by means of a separate central connector. In a system disclosed in U.S. Pat. No. 3,835,614 (Downing), the runners are generally similar to those in the Thompson system. However, in one embodiment of the Downing patent, an end of one given runner is interlocked to an intermediate section of another by means of an upwardly extending tongue. The tongue of the one runner is inserted up into a slot in the other runner and bent back so as to remain in the slot.
While each of these systems may be generally satisfactory for its intended purpose, they all have certain drawbacks relating to the way in which the individual runners are interlocked together. For example, the Jahn system and the Thompson system require separate connector or interlocking arrangements which must be assembled with the runners. Moreover, once all of the runners are interlocked together in either of these two systems, it is very difficult if not impossible to separate an individual runner from the system without separating a number of the runners. While the Downing system referred to above does not include either of these drawbacks, to interlock the runners of this latter system requires that the interlocking tabs be bent back upon themselves. This in and of itself is not believed to be desirable, particularly, inasmuch as it has the tendency of weakening the tab. In addition, to remove a runner (bending the tab back to its original position) and reusing it (again bending the tab) weakens the tab considerably. Another drawback in this embodiment of the Downing system is that any given runner is supported at its interlocked runners only by the bent over tabs.
As will be seen hereinafter, the present invention is directed to a ceiling grid system including a plurality of longitudinally extending support runners which can be interlocked together in a rapid, uncomplicated and reliable way and a way which eliminates the aforediscussed drawbacks.